Dev Blog

Summary ​

Conclusions ​

A class defines a contract for state and behavior. The constructor establishes a valid initial state, and methods and properties maintain invariants. Encapsulation conventions help developers collaborate; they do not protect against deliberate access. Object relationships and UML help explain responsibilities before all methods are written.

Self-check questions ​

  1. How does a class differ from an instance?
  2. What responsibilities do __new__ and __init__ have?
  3. How is self passed in a bound method?
  4. Why does an attribute annotation not create a value?
  5. When does an instance attribute shadow a class attribute?
  6. Why does a class-level list become shared among objects?
  7. What priority does a data descriptor have?
  8. What does __slots__ provide, and what does it not provide?
  9. How do _name and __name differ?
  10. How do you avoid recursion in a setter?
  11. When does a cached property become stale?
  12. How do you choose between a method, classmethod, and staticmethod?
  13. How do __str__ and __repr__ differ?
  14. How do you explain aggregation and composition with UML?
  15. Why does del not guarantee immediate finalization?
  1. Classes: https://docs.python.org/3.14/tutorial/classes.html.
  2. Properties: https://docs.python.org/3.14/library/functions.html#property.
  3. Descriptors: https://docs.python.org/3.14/howto/descriptor.html.
  4. Data model: https://docs.python.org/3.14/reference/datamodel.html.